Analysis of summer Antarctic sea ice anomalies associated with the spring Indian Ocean dipole

Abstract In this study, we applied the empirical orthogonal function (EOF) to analyze the anomalous characteristics of the summer Antarctic sea ice. Through correlation analysis, it is found that two strong signals existed in the spring Indian Ocean. These two signals constitute the Indian Ocean dipole (IOD). Although the IOD often occurs with El Nino-Southern Oscillation (ENSO), the first mode of the EOF is mainly resultant from the IOD. The IOD can cause sea ice anomalies in the Atlantic and Pacific Oceans, as well as the Weddell and Ross Seas. When the ENSO signal in the IOD was removed, the sea-ice anomalies in the Pacific Ocean and the eastern Ross Sea disappear, and the sea ice in the Atlantic Ocean decreases and moves westward. However, the sea ice anomalies in the Weddell Sea remain almost unchanged. These results demonstrate that the IOD excites geopotential height anomalies, causing anomalous atmospheric circulation, resulting in an increase (decrease) in sea ice caused by cold (warm) meridional flow.